The present invention is directed to a process for catalytic upgrading of the organic compounds present in the waste streams generated during the manufacture of acrylonitrile. This upgrading is carried out by catalytic oxidation or ammoxidation of the aqueous liquid waste stream containing the organic compounds.
Typical technologies for treatment and/or disposal of waste organics from the propylene ammoxidation process for manufacture of acrylonitrile include deep welling, biotreatment, and/or incineration. In addition, there are also numerous patents describing catalytic technologies for destruction of organics in waste water streams. There are many references to vapor phase processes. Non-catalytic "wet oxidation" technologies have also been reported, including U.S. Pat. No. 5,192,453 assigned to the assignee of the instant application. These methods are characterized by destruction of organics to CO.sub.2, water and inorganic nitrogen compounds; in these technologies no attempt is made to recover organics.
Hydrogen cyanide is currently manufactured by direct ammoxidation of methane (the Andrussow process) and as a byproduct of ammoxidation of propylene in the acrylonitrile process. Hydrogen cyanide can also be produced by oxidation or ammoxidation of acetonitrile, as described in Japanese Patent 59/227718 (CA 102: 168669y); Japanese Patent 59/203726 (CA 102: 133968t); Japanese Patent 49/33039 (CA 82: 61264d); West German Patent 1,146,861 (CA 59: 241b); Japanese Patent 54/71100 (CA 91: 177416v); Japanese Patent 54/71800 (CA 91: 142725t); H. Seeboth and R. Mitschke, Chem. Tech. (Leipzig), 1971, 23, 746-748; Japanese Patent 61/111913 (CA 106: 35511b); A. Ozaki, Y. Shiratsuchi, K. Mori, Kogyo Kagaku Zasshi, 1965, 68, 283-286 (CA 63: 14105e). References to HCN manufacture by cofeeding HCN with propylene in a conventional ammoxidation process include Belgian Patent 623,100 and U.S. Pat. No. 3,516,789. In U.S. Pat. No. 5,204,079 a method is described for manufacture of HCN by ammoxidation of crude acetonitrile, a co-product stream produced in the acrylonitrile manufacturing process. This crude acetonitrile stream contains some but not all of the components of acrylonitrile process waste water. In particular, crude acetonitrile as defined in the above patent does not contain the high molecular weight compounds found in relatively large amounts in acrylonitrile process waste water, and acrylonitrile and acetonitrile were not produced. HCN can also be prepared by ammoxidation or ammoniation of coal in aqueous slurry form; see G. E. Johnson, W. A. Decker, A. J. Forney, and J. H. Field, Hydrogen Cyanide from the Reaction of Coal with Ammonia, United States Department of the Interior, Bureau of Mines, Report of Investigations 6994. The composition of the organics in coal slurry is substantially different from that of the heavy organics in acrylonitrile process waste water.
While numerous methods for preparation of acetonitrile, acrylonitrile, and HCN have been reported, applicants do not know of any specific procedure for dealing with manufacture of either acrylonitrile, HCN, or acetonitrile by ammoxidation of waste water streams or mixtures of organics and water as set forth in the instant application.
Atomization of a liquid stream has been used for reducing a liquid into small droplets for ease of vaporization and reaction. An example is a fuel oil heating system. With atomization of fuel oil in a fuel oil burner, the actual combustion reaction takes place in the vapor phase at a more rapid rate than if the fuel oil were not atomized. Atomizing burners typically use a mechanical force to atomize, such as a rotary cup (Centrifugal force), auxiliary fluid (steam pressure force), and mechanical (fluid pressure). The latter two types use a nozzle design to force the fluids through small holes or slots for high velocity and turbulence which breaks the liquid into droplets. A tube carrying a high velocity gas is also well known to function as an atomizer when a liquid is injected into the flowing gas. The high velocity gas shears the liquid into droplets.